Formation of Vibrationally Excited Carbon Monosulphide and Sulphur by the Flash Photolysis of Carbon Disulphide

Nature ◽  
1960 ◽  
Vol 188 (4744) ◽  
pp. 53-54 ◽  
Author(s):  
A. B. CALLEAR ◽  
R. G. W. NORRISH
Keyword(s):  
Flash Photolysis ◽  
Carbon Disulphide ◽  
Vibrationally Excited

Flash photolysis of carbon disulphide

1963 ◽  
Vol 276 (1366) ◽  
pp. 401-412 ◽  
Keyword(s):  
Vibrational Relaxation ◽  
Flash Photolysis ◽  
Carbon Disulphide ◽  
Ultra Violet ◽  
Multiple Quantum ◽  
Vibrationally Excited ◽  
Quantum Transitions ◽  
Photochemical Decomposition ◽  
Vacuum Ultra Violet

Vibrationally excited CS is produced directly by the photochemical decomposition of CS 2 . The presence of S(3 3 P ) and the absence of S(3 1 D ) during the flash photolysis was demonstrated by vacuum ultra-violet spectroscopy. It is suggested th at collision with atomic sulphur causes a fast vibrational relaxation of CS, probably involving multiple quantum transitions. The atomic sulphur decays by polymerization and not by reaction with CS 2 .

The absorption spectrum of SO and the flash photolysis of sulphur dioxide and sulphur trioxide

1959 ◽  
Vol 249 (1259) ◽  
pp. 498-512 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Dissociation Energy ◽  
Sulphur Dioxide ◽  
Flash Photolysis ◽  
Ultra Violet ◽  
Vibrationally Excited ◽  
A Value ◽  
Continuous Absorption ◽  
Sulphur Trioxide ◽  
Normal Spectrum

The flash photolysis of sulphur dioxide under adiabatic conditions results in the complete temporary disappearance of its spectrum , which then slowly regains its original intensity over a period of several milliseconds. Simultaneously with the disappearance of the sulphur dioxide spectrum a continuous absorption appears in the far ultra-violet and fades slowly as the sulphur dioxide reappears. It is shown that the effect of the flash is thermal rather than photochemical, and the possibility of the existence of an isomer of sulphur dioxide at high temperatures is discussed; the disappearance of the normal spectrum on flashing is explained in this way. Several previously unrecorded bands of SO observed in the photolysis indicate that the vibrational numbering of its spectrum should be revised by the addition of 2 to the present values of v' . This leads to a value of the dissociation energy of 123.5 kcal. In formation about the levels v' = 4, 5 and 6 has also been obtained. The isothermal flash photolysis of sulphur trioxide results in the appearance of vibrationally excited SO, and the primary photochemical step in this reaction is discussed.

Energy disequilibrium in the flash photolysis of NO 2

1973 ◽  
Vol 334 (1599) ◽  
pp. 553-568 ◽  
Keyword(s):  
Nitric Oxide ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Dissociation Limit ◽  
Primary Process ◽  
Transfer Energy ◽  
Vibrationally Excited ◽  
Absolute Concentrations ◽  
The Absolute ◽  
Excited Oxygen

From measurements of the absolute concentrations of vibrationally excited oxygen produced in levels v" = 4 to v" = 13, it is concluded that ca . 20 % of the exothermicity of the reaction O( 3 P) + NO 2 → NO + O + 2 ( v" ≤11) (1) appears initially as vibrational energy in oxygen. Vibrationally excited nitric oxide ( v" = 1, 2) is also observed and may be produced in this reaction or in the primary process NO 2 + hv → NO ( v" ≤ 2) + O( 3 P). More highly excited oxygen ( v" ≤ 15), with energy exceeding the exothermicity of the reaction, is produced in reaction (1) when the NO 2 is first excited by radiation above the dissociation limit near 400 nm. The excited NO 2 thus produced can also transfer energy to nitric oxide. NO 2 * + NO( v" = 0) → NO 2 + NO( v" = 1).

Vibrationally Excited Ozone in the Pulse Radiolysis and Flash Photolysis of Oxygen

1968 ◽  
Vol 48 (6) ◽  
pp. 2416-2420 ◽  
Author(s):  
C. J. Hochanadel ◽  
J. A. Ghormley ◽  
J. W. Boyle
Keyword(s):  
Pulse Radiolysis ◽  
Flash Photolysis ◽  
Vibrationally Excited

Reactions of halogen oxides studied by flash photolysis II. The flash photolysis of chlorine monoxide and of the ClO free radical

1971 ◽  
Vol 323 (1554) ◽  
pp. 401-415 ◽  
Keyword(s):  
Free Radical ◽  
Quantum Yield ◽  
Rate Constant ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Vibrationally Excited ◽  
Chlorine Atoms ◽  
Chlorine Monoxide ◽  
Halogen Oxides ◽  
Excited Oxygen

A study of the flash photolysis of chlorine monoxide and of its photosensitized decomposition by chlorine and bromine has yielded rate constants for the reactions Cl + Cl 2 O → Cl 2 + ClO, k 1 = 4.1 x 10 8 l mol -1 s -1 , Br + Cl 2 O → BrCl + ClO, k 9 = 6.1 x 10 8 l mol -1 s -1 , ClO + Cl 2 O → ClO 2 + Cl 2 , k 3 = 2.6 x 10 5 l mol -1 s -1 , ClO + Cl 2 O → Cl 2 + O 2 + Cl, k 4 = 6.5 x 10 5 l mol -1 s -1 , 2ClO → Cl 2 + O 2 , k 2 = 2.8 x 10 7 l mol -1 s -1 . The quantum yield for the decomposition of chlorine monoxide was measured in each of the three systems and is quantitatively accounted for by the reactions given. The CIO free radical has been flash photolysed and the production of vibrationally excited oxygen in the reaction O + CIO → Cl + O* 2 ( v" ≼ 14), k 11 = 7.5 x 10 9 l mol -1 s -1 demonstrated. The same reaction is responsible for the production of O* 2 in the flash photo­lysis of Cl 2 O with radiation below ~ 300 nm. The relaxation of O* 2 by chlorine atoms is exceptionally efficient, with a rate constant for v" = 12 in excess of 2 x 10 9 l mol -1 s -1 . The corresponding rate constant for relaxation by Cl 2 O is < 10 8 l mol -1 s -1 .

Flash photolysis and spectroscopy. A new method for the study of free radical reactions

1950 ◽  
Vol 200 (1061) ◽  
pp. 284-300 ◽  
Keyword(s):  
Flash Photolysis ◽  
Carbon Disulphide ◽  
Luminous Efficiency ◽  
Physical Methods ◽  
Short Intervals ◽  
Discharge Tubes ◽  
Photochemical Decomposition ◽  
A New Technique ◽  
Photochemical Systems ◽  
Very High

Photochemistry provides us with one of the most generally useful methods of studying the reactions of free radicals and atoms, but the concentration of these intermediates in the usual photochemical systems is too low to allow the use of direct physical methods of investigation such as absorption spectroscopy. To overcome this difficulty a new technique of flash photolysis and spectroscopy has been developed, using gas-filled flash discharge tubes of very high power. The properties of these lamps as spectroscopic and photochemical sources have been studied and details are given of their construction, spectra, duration of flash, and luminous efficiency in the photochemicaliy useful region. An apparatus is described which produces a very great photochemical change, in some cases over 80%, in one-thousandth of a second and in a gas at several cm. pressure contained in an absorption tube 1 m. long, and which photographs the absorption spectrum at high resolution in one twenty-thousandth of a second at short intervals afterwards. Examples of the rapidly changing spectra of substances undergoing reaction, including the spectra of some of the intermediate radicals involved, are shown. These include the recombination of chlorine atoms, the absorption Spectra of S 2 and CS obtained during the photochemical decomposition of carbon disulphide and new spectra attributed to the CIO and CH 3 CO radicals.

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